Index: src/wp-includes/formatting.php
===================================================================
--- src/wp-includes/formatting.php	(revision 49504)
+++ src/wp-includes/formatting.php	(working copy)
@@ -4300,7 +4300,7 @@
  * @param string[] $protocols Optional. An array of acceptable protocols.
  *                            Defaults to return value of wp_allowed_protocols().
  * @param string   $_context  Private. Use esc_url_raw() for database usage.
- * @return string The cleaned URL after the {@see 'clean_url'} filter is applied.
+ * @return string The cleaned URL after the {@see 'clean_url'} filter is applied. Returns an empty string if an invalid $protocol is found in the $url.
  */
 function esc_url( $url, $protocols = null, $_context = 'display' ) {
 	$original_url = $url;
@@ -4408,7 +4408,7 @@
  * @param string   $url       The URL to be cleaned.
  * @param string[] $protocols Optional. An array of acceptable protocols.
  *                            Defaults to return value of wp_allowed_protocols().
- * @return string The cleaned URL.
+ * @return string The cleaned URL after {@see 'esc_url()'} is run with the 'db' context.
  */
 function esc_url_raw( $url, $protocols = null ) {
 	return esc_url( $url, $protocols, 'db' );